Surface Roughness And Colour Stability Of Dental Porcelain Treated With Different Polishing Methods

Background: The study aims to investigate the effect of different polishing methods on the dental porcelain surface roughness and tea extract staining resistance. Methods: A total of 40 disc-shaped dental porcelain of 10mm diameter and 2mm thickness were divided into four groups: Group A (Glaze), untreated control; Group B (Polishing paste), using slow speed green stone bur and followed by diamond polishing paste; Group C (NTI), using NTI CeraGlaze polishing kits; and Group D (Identoflex), using Identoflex Diamond Ceramic Polisher. The specimens were then subjected to a baseline measurement for surface roughness and colour shade using a surface profilometer and digital spectrophotometer, respectively. The glaze layer was removed using a medium-grit diamond rotary bur, followed by 60 seconds polishing according to the assigned method. A second surface roughness measurement ensued. The specimens were then subjected to thermal cycling between 5°C and 55°C for 2000 cycles, followed by 30 days staining in a tea extract solution. A second colour shade measurement ensued. Results: The surface roughness of dental porcelain was highest in the Polishing paste group (p < 0.05), and the NTI and Identoflex group were not significantly different from the Glaze group (p > 0.05). In all test groups, the Glaze group shows superiority in colour stability with DE value significantly higher compared to all test group (p < 0.05). Conclusion: Although the mechanical polishing can restore the smoothness of the glazed surface, it cannot restore the ability to resist tea extract staining.